Iliac vein stenting is a promising new approach to treat patients with a variety of chronic venous diseases. The stents currently used are prone to compression/migration of the upper end of the stent (at the iliac-caval junction, for example, which is a choke point) requiring reintervention in a significant number of cases (10-20%). These stent ‘end effects’ are particularly common when treating lesions at or near the iliac-caval junction and the stent is attempted to be placed ‘precisely’ at the junction to avoid stent encroachment of vena cava proper. Both primary and postthrombotic lesions occur frequently at this location.
Constriction of the stent diameter by as much as 30% can occur due to recoil in some lesions despite adequate predilatation, leading to unpredictable stent length. It is also common to observe the upper end of the stent “squeezed” downward by a tight lesion and retracted axially.
Precise stent placement across this lesion is difficult, because of the variability of the lesion length, and also because of the anatomic variability of the arterial and venous bifurcations. Venography is the current standard for visualizing the anatomy of the vein but it is a poor guide to assess these variabilities.
Although intravascular ultrasound (IVUS) is more accurate than venography and provides local assessment of geometric complexities, it cannot assess the compliance of the vein (as it does not interrogate the vein under stent-like radial force conditions), and it is quite expensive and requires detailed training. Hence, there is a significant need for a technology that can assess the lumen profile, namely the variation in cross-sectional area (CSA) along the length of one or more veins, for example, along with the axial variation in the compliance of the veins (and radial force) to assess the degree of external compression on the vein of interest.